Splitting guestcode

Changes:
 - git-subtree-dir: guest
 - git-subtree-mainline: 2daad86fa934f3b76df1ec8be44dcbab86550d83
 - git-subtree-split: 487c346e6b4b51f7f0ea1902307542cbfff0de65

Implements: blueprint separate-guestagent-related-code